Mechanical properties variation and constitutive modelling of biomedical polymers after sterilization.

PURPOSE In this work, the mechanical behavior of two block copolymers for biomedical applications is studied with particular regard to the effects induced by a steam sterilization treatment that biomedical devices usually undergo in healthcare facilities. This investigation is aimed at describing the elasto-plastic behavior of the stress-strain response, determining a functional dependence between material constitutive parameters, to obtain an optimal constitutive model. METHODS The mechanical properties of these polymers are analyzed through uniaxial tensile tests, before and after the sterilization process. The effect of sterilization on the mechanical behavior is evaluated. The Ramberg-Osgood model is used to describe the elasto-plastic behavior of the stress-strain response. RESULTS Data from uniaxial tensile tests are discussed in the light of previous data on the same polymeric materials, in order to highlight the correlation between physicochemical and mechanical properties variation. The material constitutive parameters are determined and the functional dependence between them is found, thus enabling an optimal constitutive model to be obtained. CONCLUSIONS The effect of sterilization on the material constitutive parameters is studied, to evaluate the suitability of the model in describing the mechanical response of biomedical polymer before and after sterilization treatment. The same approach can be applied to other biomaterials, under various tensile tests, and for several processes that induce variation in mechanical properties.